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Fig. 2 | Clinical and Translational Medicine

Fig. 2

From: PI3K inhibitors in thrombosis and cardiovascular disease

Fig. 2

Overview of the PI3K complexes and their activities. Class I PI3Ks form heterodimers comprised of a catalytic subunit and a regulatory subunit, although free Class IA regulatory subunits also exist in cells. In vivo, Class I PI3Ks 3-phosphorylate PtdIns(4,5)P2 to generate PtdIns(3,4,5)P3. Class II PI3Ks appear to function as independent catalytic subunits, and are currently considered to 3-phosphorylate PtdIns and PtdIns(4)P in vivo to yield PtdIns(3)P and PtdIns(3,4)P2, respectively. However, Class II PI3K-deficient mouse models suggest PI3KC2α may only act to regulate a housekeeping pool of PtdIns(3)P in platelets, while PI3KC2β has no clear functional role, and PI3KC2γ is not expressed in this cell type. Class III PI3K, VPS34, associates with various proteins to form at least two known complexes, although it is likely that other associations and complexes exist. Class III PI3K phosphorylates PtdIns to generate PtdIns(3)P. Class I, II and III PI3Ks all play roles in platelet thrombus formation, and the predominant role of each is detailed

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